1. Field of the Invention
This invention relates to an optical type scanning microscope. This invention particularly relates to a scanning microscope, which can form an ordinary bright field image and a dark field image. This invention also relates to a confocal scanning microscope with which dark field photometry can be carried out.
2. Description of the Prior Art
Optical type scanning microscopes have heretofore been used. With the scanning microscope, a light beam is converged to a small light spot on a sample, and the sample is two-dimensionally scanned with the light spot. The light beam, which has passed through the sample during the scanning, the light beam, which has been reflected from the sample during the scanning, or the fluorescence, which is produced by the sample during the scanning, is detected by a photodetector. An enlarged image of the sample is thereby obtained. An example of the scanning microscope is disclosed in Japanese Unexamined Patent Publication No. 62(1987)-217218.
As one type.of the scanning microscopes, a confocal scanning microscope has heretofore been proposed. With the confocal scanning microscope, a light beam is produced by a light source and is condensed to a light spot such that an image of the light spot is formed on a sample. Also, a point image of the light beam, which has been radiated out of the sample, is formed and detected by a photodetector. The confocal scanning microscope is advantageous in that no pinhole plate need be located on the surface of the sample. An example of the confocal scanning microscope is disclosed in Japanese Unexamined Patent Publication No. 62(1987)-217218.
Such that a very small object image beyond the resolution can be discerned, it has also been proposed to employ a dark field photometric technique in optical type scanning microscopes. Basically, the dark field photometric type of scanning microscope comprises:
(i) a light source which produces a light beam, PA1 (ii) a sample supporting member on which a sample is supported, PA1 (iii) a light projecting optical means with which an image of the light beam is formed as a small light spot on the sample, PA1 (iv) a light receiving optical means, which is provided with a beam trap for trapping the direct light beam having passed through the object and with which the light beam scattered by the sample is condensed, an image of the condensed light beam being thereby formed as a point image, PA1 (v) a photodetector which detects the point image, and PA1 (vi) a scanning mechanism for two-dimensionally scanning the sample with the light spot. PA1 (i) a sample supporting member on which a sample is supported, PA1 (ii) a light source for producing a light beam including a light component, which has been polarized linearly in a first direction, and a light component, which has been polarized linearly in a second direction that intersects perpendicularly to said first direction, PA1 (iii) a first polarizer which has a predetermined shape, said first polarizer transmitting only said light component, which has been polarized linearly in said first direction, therethrough, PA1 (iv) a second polarizer for transmitting only said light component, which has been polarized linearly in said second direction, therethrough, PA1 (v) a light projecti image of the light beam composed of said light components, which have respectively passed through said first polarizer and said second polarizer, said image being formed as a small light spot on said sample, PA1 (vi) a scanning means which causes said light spot to scan said sample two-dimensionally, PA1 (vii) a beam trap having a light blocking part which has a shape corresponding to the shape of said first polarizer, said beam trap blocking only the direct light component, which has been polarized linearly in said first direction, said direct light component having passed through said sample, PA1 (viii) a polarization beam splitter for separating said light component, which has been polarized linearly in said first direction, and said light component, which has been polarized linearly in said second direction, from each other, two said light components being included in part of said light beam, which part has passed through said sample and then through said beam trap, PA1 (ix) a first light receiving optical means for condensing said light component, which has been polarized linearly in said first direction, said light component having been separated by said polarization beam splitter from said light component, which has been polarized linearly in said second direction, an image of the condensed light component being thereby formed as a point image, PA1 (x) a second light receiving optical means for condensing said light component, which has been polarized linearly in said second direction, said light component having been separated by said polarization beam splitter from said light component, which has been polarized linearly in said first direction, an image of the condensed light component being thereby formed as a point image, PA1 (xi) a first photodetector for detecting said point image, which has been formed by said first light receiving optical means, and PA1 (xii) a second photodetector for detecting said point image, which has been formed by said second light receiving optical means. PA1 (i) a sample supporting member on which a sample is supported, PA1 (ii) a light source for producing a light beam including a light component, which has been polarized linearly in a first direction, and a light component, which has been polarized linearly in a second direction that intersects perpendicularly to said first direction, PA1 (iii) a stop member provided with an opening which has a predetermined shape, said stop member stopping said light beam, PA1 (iv) a light projecting optical means for forming an image of part of said light beam, which part has passed through said stop member, said image being formed as a small light spot on said sample, PA1 (v) a scanning means which causes said light spot to scan said sample two-dimensionally, PA1 (vi) a first analyzer for transmitting only said light component, which has been polarized linearly in said first direction, therethrough, said light component having passed through said sample, PA1 (vii) a second analyzer which has a shape corresponding to the shape of said opening of said stop member, said second analyzer transmitting only the direct light component, which has been polarized linearly in said second direction, therethrough, said light component having passed through said sample, PA1 (viii) a polarization beam splitter for separating said light component, which has been polarized linearly in said first direction, said light component having passed through said first analyzer, and said light component, which has been polarized linearly in said second direction, said light component having passed through said second analyzer, from each other, PA1 (ix) a first light receiving optical means for condensing said light component, which has been polarized linearly in said first direction, said light component having been separated by said polarization beam splitter from said light component, which has been polarized linearly in said second direction, an image of the condensed light component being thereby formed as a point image, PA1 (x) a second light receiving optical means for condensing said light component, which has been polarized linearly in said second direction, said light component having been separated by said polarization beam splitter from said light component, which has been polarized linearly in said first direction, an image of the condensed light component being thereby formed as a point image, PA1 (xi) a first photodetector for detecting said point image, which has been formed by said first light receiving optical means, and PA1 (xii) a second photodetector for detecting said point image, which has been formed by said second light receiving optical means. PA1 (i) a sample supporting member on which a sample is supported, PA1 (ii) a light source for producing a light beam including a light component, which has a first wavelength, and a light component, which has a second wavelength different from said first wavelength, PA1 (iii) a first filter which has a predetermined shape, said first filter transmitting only said light component, which has said first wavelength, therethrough, PA1 (iv) a second filter for transmitting only said light component, which has said second wavelength, therethrough, PA1 (v) a light projecting optical means for forming an image of the light beam composed of said light components, which have respectively passed through said first filter and said second filter, said image being formed as a small light spot on said sample, PA1 (vi) a scanning means which causes said light spot to scan said sample two-dimensionally, PA1 (vii) a beam trap having a light blocking part which has a shape corresponding to the shape of said first filter, said beam trap blocking only the direct light component, which has said first wavelength, said direct light component having passed through said sample, PA1 (viii) a light splitting means for separating said light component, which has said first wavelength, and said light component, which has said second wavelength, from each other, two said light components being included in part of said light beam, which part has passed through said sample and then through said beam trap, PA1 (ix) a first light receiving optical means for condensing said light component, which has said first wavelength, said light component having been separated by said light splitting means from said light component, which has said second wavelength, an image of the condensed light component being thereby formed as a point image, PA1 (x) a second light receiving optical means for condensing said light component, which has said second wavelength, said light component having been separated by said light splitting means from said light component, which has said first wavelength, an image of the condensed light component being thereby formed as a point image, PA1 (xi) a first photodetector for detecting said point image, which has been formed by said first light receiving optical means, and PA1 (xii) a second photodetector for detecting said point image, which has been formed by said secqnd light receiving optical means. PA1 (i) a sample supporting member on which a sample is supported, PA1 (ii) a light source for producing alight beam including a light component, which has afirst wavelength, and a light component, whichhas a second wavelength different from said first wavelength, PA1 (iii) a stop member provided with anopening which has a predetermined shape, said stop member stopping said light beam, PA1 (iv) a light projecting optical means for forming an image of part of said light beam, which part has passed through said stop member, said image being formed as a small light spot on said sample, PA1 (v) a scanning means which causes said light spot to scan said sample two-dimensionally, PA1 (vi) a first filter for transmitting only said light component, which has, said first wavelength, therethrough, said light component having passed through said sample, PA1 (vii) a second filter which has a shape corresponding to the shape of said opening of said stopmember, said second filter transmitting only the direct light component, which has said second wavelength, therethrough, said direct light componenthaving passed through said sample, PA1 (viii) a light splitting means for separating said light component, which has said first wavelength, said light component having passed through said first filter, and said light component, which has said second wavelength, said light component having passed through said second filter, from each other, PA1 (ix) a first light receiving optical means for condensing said light component, which has said first wavelength, said light component having been separated by said light splitting means from said light component, which has said second wavelength, an image of the condensed light component being thereby formed as a point image, PA1 (x) a second light receiving optical means for condensing said light component, which has said second wavelength, said light component having been separated by said light splitting means from said light component, which has said first wavelength, an image of the condensed light component being thereby formed as a point image, PA1 (xi) a first photodetector for detecting said point image, which has been formed by said first light receiving optical means, and PA1 (xii) a second photodetector for detecting said point image, which has been formed by said second light receiving optical means. PA1 (i) a sample supporting member on which a sample is supported, PA1 (ii) a light source which produces a light beam, PA1 (iii) a light projecting optical means with which an image of said light beam is formed as a small light spot on said sample, PA1 (iv) a light receiving optical means with which the light beam having passed through said sample is condensed, and an image of the condensed light beam is formed as a point image, PA1 (v) a scanning means which causes said light spot to scan said sample two-dimensionally, PA1 (vi) a beam splitting means for splitting said light beam, which has been produced by said light source, into a light beam, which is to be irradiated to said sample, and a reference light beam, which is not to be irradiated to said sample, before said light beam having been produced by said light source impinges upon said sample, PA1 (vii) a beam combining means for combining said light beam, which has passed through said sample, and said reference light beam with each other, PA1 (viii) a first modulation means for modulating said light beam, which has been radiated out of said beam splitting means and which is to be irradiated to said sample, with a first modulation frequency, PA1 (ix) a second modulation means for modulating said reference light beam with a second modulation frequency, which is different from said first modulation frequency, PA1 (x) a photodetector for detecting the combined light beam, which has been radiated out of said beam combining means, and PA1 (xi) a filter means for obtaining a signal by eliminating beat components, which result from the modulated light beam and the modulated reference light beam, from an output signal generated by said photodetector.
It is rarely that users of scanning microscopes desire to obtain only dark field images. In general, in cases where it is desired for dark field images to be formed, it is also desired that ordinary bright field images can also be formed.
Therefore, in cases where it is desired for the dark field photometric technique to be carried out in an optical type scanning microscope, the optical type scanning microscope have heretofore been provided with both an optical means for the ordinary bright field photometric technique and an optical means for the dark field photometric technique, in which a beam trap is included. The two optical means are used selectively such that a bright field image or a dark field image may be formed.
However, considerable time and labor are required to change over the optical means used in the optical type scanning microscope. Such change-over operations have been a heavy burden to the operators who uses the microscopes.
Also, it is desirable that the state of a sample at any given instant can be investigated by viewing both the bright field image and the dark field image of the sample. However, in cases where the optical means for the ordinary bright field photometric technique and the optical means for the dark field photometric technique is used selectively, even if the operation for changing over the optical means is carried out as quickly as possible, it is impossible for both the bright field image and the dark field image of the sample at exactly the same instant to be obtained.
Additionally, it has been proposed to support a light projecting optical means and a light receiving optical means on a single movable member, and to scan a sample, which is placed on a sample supporting member, with a light spot of a light beam by moving the movable member with respect to the sample supporting member. Such a technique is proposed in, for example, U.S. patent application Ser. No. 587,122. In such cases, if a beam trap is employed in the optical means, the movable member becomes heavy, and therefore the scanning with the light spot of the light beam cannot be carried out quickly.